There's no ideal diet that's right for everyone, but that shouldn't stop the nation's doctors from helping their heavy patients battle weight issues as aggressively as things like blood pressure, according to new obesity treatment guidelines out Tuesday.

The guidelines, from three leading health groups, say that doctors need to help obese patients figure out the best plan, whether it's a vegetarian diet, low-sodium plan, commercial weight-loss program or a low-carb diet.

Still, the most effective behavior-change weight-loss programs include two to three in-person meetings a month for at least six months, and most people should consume at least 500 fewer calories a day to lose weight, the recommendations say.

The guidelines are designed to help health care providers aggressively tackle the obesity epidemic. "The overall objective is quite a tall order: to get primary care practitioners to own weight management as they own hypertension management," says obesity researcher Donna Ryan, co-chairwoman of the committee writing these guidelines for the Obesity Society, American Heart Association and American College of Cardiology.

The recommendations are part of a set of heart disease prevention guidelines that also include new cholesterol guidelines, healthy lifestyle guidance and recommendations for calculating cardiovascular risk.

Nearly 155 million U.S. adults are overweight or obese, which is roughly 35 pounds over a healthy weight. Extra pounds put people at a higher risk of heart disease, stroke, many types of cancer, type 2 diabetes and a host of other health problems.

Health care providers should encourage obese and overweight patients who need to drop pounds for health reasons to lose at least 5% to 10% of their weight by following a moderately reduced-calorie diet suited to their food tastes and health status, while being physically active and learning behavioral strategies.

"The gold standard is an intervention delivered by trained interventionists (not just registered dietitians or doctors) for at least 14 sessions in the first six months and then continue therapy for a year," says Ryan, a professor emeritus at the Pennington Biomedical Research Center in Baton Rouge. If this kind of intensive therapy is not available, then other types of treatment, such as commercial weight-loss programs or telephone and Web-based programs, are good "second choices," she says. The new guidelines are based on the latest scientific evidence from 133 research studies.

Medicare began covering behavioral counseling for obese patients last year, and under the Affordable Care Act, most private insurance companies are expected to cover behavioral counseling and other obesity treatments by next year.

"There is no ideal diet for weight loss, and there is no superiority between the many diets we looked at," Ryan says. "We examined about 17 different weight-loss diets. There are many dietary paths to weight loss, as long as you are creating a calorie deficit."

For example, a person with high blood cholesterol might benefit from a diet lower in calories and saturated (animal) fat; a person with high blood pressure should consider a diet low in sodium, such as the DASH diet, she says. Vegetarians can lose weight on a lower-calorie version of that plan, she says. Those who prefer an Atkins-type low-carb diet can be successful with that approach and should not be discouraged from using it, she says.

Pat O'Neil, director of the Weight Management Center at Medical University of South Carolina, says, "These guidelines are based on a thorough review of scientific studies. There is a no single right diet for weight loss. The diet you follow is the one that's going to work for you. That's good information for the public to have."

The report advises health care providers to calculate body mass index (a number that takes into account height and weight) at annual visits or more frequently, and use it to identify adults who may be at a higher risk of heart disease and stroke because of their excess pounds. Evidence shows that the greater the BMI, the higher the risk of coronary heart disease, stroke, type 2 diabetes and death from any cause, the report says. "BMI is a quick and easy first step," Ryan says.

The obesity-treatment recommendations are being discussed this week at the annual meeting of The Obesity Society. The guidelines say:

• Modest amounts of weight loss provide health benefits. "Our review showed that there were health benefits beginning at loss of as little as 3% to 5%, but bigger losses provide bigger benefits," Ryan says. "We want patients to achieve weight loss of 5%-10%, and for any attempt, the goal is usually 10%. This is still modest weight loss, and it can produce dramatic improvement in reducing the risk of developing type 2 diabetes, as well as reducing blood pressure, triglycerides (blood fats), blood glucose and other risk factors for heart disease."

• Diet alone is not recommended. People should do moderate physical activity, working up to doing at least 150 minutes per week. They should also get behavioral counseling.

• Bariatric surgery may provide significant health benefits for adults with a BMI of 40 or higher, and patients with a BMI of 35 or higher who have other cardiovascular risk factors such as diabetes or high blood pressure. The guidelines do not recommend one type of surgery over another.

The guidelines are being published simultaneously in Circulation, a journal of the American Heart Association; the Journal of the American College of Cardiology; and Obesity: Journal of The Obesity Society.